Phosphonite ligands and their use in hydrocyanation

ABSTRACT

Disclosed herein are processes for hydrocyanation and isomerization of olefins by using at least one multidentate phosphonite ligands, including organometallic phosphonite ligands with a Group VIII metal or Group VIII metal compound, and optionally, a Lewis acid promoter.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of co-pending application Ser.No. 10/093,655, originally filed on Mar. 7, 2002, in the names ofChristian P: Lenges, Helen S. M. Lu and Joachim C. Ritter.

FIELD OF THE INVENTION

[0002] The present invention concerns the use of catalyst compositionscomprising a Group VIII metal and a multidentate phosphonite ligand forolefinic hydrocyanation and isomerization processes.

BACKGROUND OF THE INVENTION

[0003] Certain phosphonites have been used as a part of hydrocyanationcatalyst systems. U.S. Pat. No. 5,817,850 discloses the use of acatalyst composition in hydroformylation and hydrocyanation reactions.WO9843935 discloses the use of certain phosphonite ligands as part of acatalyst system in a process for producing an aldehyde. WO9946044relates to a hydroformylation process using phosphonite ligands as partof the catalyst system for hydroformylation reactions. U.S. Pat. No.6,242,633 discloses a process for the production of nitriles usingcatalysts containing phosphonite ligands. Further, WO9964155 disclosesuse of catalysts containing phosphorous ligands in hydrocyanationreactions.

[0004] Despite the disclosure of various ligands in hydrocyanation andhydroformylation processes. Catalyst compositions comprising certainmultidentate phosphonite ligands show effectiveness and/or higherperformance and achieve improvements in rapidity, selectivity,efficiency or stability.

SUMMARY OF THE INVENTION

[0005] A hydrocyanation process, said process comprising: contacting anethylenically unsaturated olefin compound with HCN in the presence of acatalyst composition, wherein said catalyst composition comprises aGroup VIII metal and a phosphonite ligand wherein the ligand having astructure selected from the group consisting of:

[0006] wherein the X groups are either the same or different unbridgedorganic aromatic groups as described in Formula I, wherein Q is asubstituted or unsubstituted divalent aromatic or non aromatichydrocarbon radical. The substituent on the Q groups is independentlyselected from the group consisting of C1 to C12 alkyl, cycloalkyl,alkoxy, alkylaryl, aryl, hetero aryl, cyano or

[0007] The use of a catalyst based on a ligand of structure II for thehydrocyanation and/or the positional isomerization or double bondisomerization of olefins.

DETAILED DESCRIPTION

[0008] The present invention describes a hydrocyanation processcomprising: contacting an ethylenically unsaturated olefin compound withHCN in the presence of a catalyst composition, wherein the catalystcomposition comprises a Group VIII metal and a phosphonite ligand havinga structure selected from the group consisting of:

[0009] wherein the X groups are either the same or different unbridgedorganic aromatic groups as described in Formula I, wherein Q is asubstituted or unsubstituted divalent aromatic or non aromatichydrocarbon radical; and when Q is substituted, the substituent on the Qgroup is independently selected from the group consisting of C1 to C12alkyl, cycloalkyl, alkoxy, alkylaryl, aryl, hetero aryl, cyano.

[0010] Typical X for structure II include but are not limited to:

[0011] The hydrocyanation process described herein may be carried out inthe presence of a catalyst precursor composition comprising a Group VIIImetal and at least one multidentate phosphonite ligand having astructure II I as described above and optionally a Lewis acid.

[0012] Generally, a Group VII metal or a compound thereof is combinedwith at least one of the ligand structure II to provide the catalyst.Among the Group VII metal compounds, nickel, cobalt, and palladiumcompounds are preferred for hydrocyanation catalysts. A nickel compoundis more preferred, and a zero-valent nickel compound having a ligandthat can be chemically displaced by the ligand structure of the presentinvention is the most preferred source of Group VIII metal or Group VIIImetal compound.

[0013] Zero-valent nickel compounds that can be used for preparing thecatalyst of the present invention are disclosed in the art. Thepreferred zero-valent nickel compounds are Ni(COD)₂ (COD is1,5-cyclooctadiene), Ni(P(O-o-C₆H₄CH₃)₃)₃ andNi{P(O-o-C₆H₄CH₃)₃}₂(C₂H₄), all of which are known in the art.

[0014] The catalyst of the present invention is prepared by combiningthe zero-valent nickel compound with at least one molar equivalent ofthe ligand of structure II of the present invention in a ratio ofnickel:bidentate ligand of 1:1. The ligand may be combined with nickelin a solvent, or preferably in the substrate medium. Suitable solventsinclude, but are not limited to, hydrocarbons such as benzene, xylene,or combinations thereof; ethers such as tetrahydrofuran (THF); nitrilessuch as acetonitrile, benzonitrile, adiponitrile, or combinations of twoor more thereof. The unsaturated olefin used in the hydrocyanationprocess may itself serve as the solvent. The catalyst preparation may bedone at room temperature, or at a temperature that is appropriate forthe solvent being used, or the hydrocyanation process conditions.

[0015] Alternatively, divalent nickel compounds can be combined with areducing agent, to serve as a source of zero-valent nickel in thereaction. Suitable divalent nickel compounds include compounds of theformula NiZ² ₂ where Z² is halide, carboxylate, or acetylacetonate.Suitable reducing agents include metal borohydrides, metal aluminumhydrides, metal alkyls, Li, Na, K, Zn or H₂.

[0016] The divalent nickel compound is combined with the ligandstructure II of the present invention in a suitable solvent, preferablythe unsaturated olefin, in a ratio of 1:1, or preferably at least 2:1.The combination is then combined with a suitable reducing agent at roomtemperature, or at a temperature that is appropriate for the solventbeing used, or the hydrocyanation process conditions being used. Theresulting catalyst composition may be isolated, if desired.

[0017] Hydrocyanation Using Phosphorus-Containing Ligands of the PresentInvention:

[0018] The catalyst compositions of the present invention may be usedwith or without a Lewis acid in the hydrocyanation of organic compounds.The hydrocyanation process comprises contacting, in the presence of thecatalyst, an olefinic unsaturated organic compound with a hydrogencyanide-containing fluid under conditions sufficient to produce anitrile, wherein the catalyst comprises a Group VIII metal, at least oneof the ligands described above, and optionally a Lewis acid as apromoter. As used herein, the term “fluid” means gas, a liquid, or acombination of these. Any fluid containing about 1 to 100% HCN can beused.

[0019] A particularly significant use of the ligands of the presentinvention is in the hydrocyanation of olefins. In such a process, anolefinic compound such as a diolefinic compound can be converted to anitrile or a dinitrile, or a combination thereof. The hydrocyanationprocess can be carried out, for example, by charging a suitable vesselwith an olefin, catalyst composition, and solvent, if used, to form areaction mixture. Hydrogen cyanide can be combined initially with othercomponents to form the mixture. However, it is preferred that HCN beadded slowly to the mixture after other components have been combined.Hydrogen cyanide can be delivered as a liquid or as a vapor to thevessel. As an alternative, a cyanohydrin can be used as the source ofHCN. See, for example, U.S. Pat. No. 3,655,723, incorporated herein byreference.

[0020] Another suitable technique is to charge the vessel with thecatalyst and the solvent (if any) to be used, and feed both theunsaturated compound and the HCN slowly to the reaction mixture.

[0021] The molar ratio of ethylenically unsaturated olefin compound tocatalyst can be varied from about 10:1 to about 10000:1. The molar ratioof HCN to catalyst generally is varied from about 10:1 to 100,000:1,preferably 100:1 to 5,000:1, for a batch operation. In a continuousoperation, such as when using a fixed bed catalyst type of operation, ahigher proportion of catalyst can be used such as a molar ratio of about5:1 to about 100,000:1, and preferably about 100:1 to about 5,000:1, HCNto catalyst.

[0022] Preferably, the reaction mixture is agitated, for example, bystirring or shaking. The reaction product can be recovered byconventional techniques such as distillation. The process can be runeither batchwise or continuously.

[0023] The hydrocyanation can be carried out with or without a solvent.The solvent, if used, can be liquid at the reaction temperature andpressure and inert towards the olefin and the catalyst. Suitablesolvents include, but are not limited to, hydrocarbons such as benzene,xylene, or combinations thereof; ethers such as tetrahydrofuran (THF);nitriles such as acetonitrile, benzonitrile, adiponitrile, orcombinations of two or more thereof. The unsaturated olefin to behydrocyanated can itself serve as the solvent. Hydrocyanation can alsobe carried out in the gas phase.

[0024] The exact temperature is dependent to a certain extent on theparticular catalyst being used, the particular olefin being used and thedesired reaction rate. Normally, temperatures of from about −25° C. toabout 200° C. can be used with the range of 0° C. to 150° C. beingpreferred.

[0025] Atmospheric pressure is suitable for carrying out the reaction,and hence pressures of from about 0.05 to 10 atmospheres (50.6 to 1013kPa) are preferred. Higher pressures, up to 10,000 kPa or more, can beused, if desired, but any benefit that may be obtained thereby wouldprobably not justify the increased cost of such operations.

[0026] The time required can be in the range of from a few seconds tomany hours (such as 2 seconds to 24 hours), depending on the particularconditions and method of operation.

[0027] The ethylenically unsaturated olefin compound is acyclic andaliphatic, or a combination of two or more ethylenically unsaturatedolefin compounds that each are acyclic and aliphatic. A non-limitingexample of these compounds is shown in Formula IV, and the correspondingnitrile compound produced by the hydrocynation process is shown byFormula V, respectively.

[0028] The ethylenically unsaturated olefin has 2 to about 30 carbonatoms per molecule and has the formula selected from the groupconsisting of R₃CH═CH—CH═CR₄, CH═CH—(CH₂)_(q)—R₅,CH₃—(CH₂)_(n)—CH═CH—(CH₂)_(q)—R₆, and combinations of two or morethereof, wherein R₃ and R₄ are each independently H, C1 to C3 alkyl, orcombinations thereof; R₅ is H, CN, CO₂R₈, perfluoroalkyl having 1 toabout 20 carbon atoms; n is an integer of 0 to 12; q is an integer of 0to 12 when R₆ is H or perfluoroalkyl, and q is an integer of 1 to 12when R₆ is CO₂R₇, CN; and R₇ is C1 to C12 alkyl or cycloalkyl, C6 to C20aryl, or combinations thereof.

[0029] Examples of suitable olefins include ethylenically unsaturatedcompounds such as ethylene, propylene, 1-butene, 2-pentene, 2-hexene,and combinations of two or more thereof; non-conjugated diethenicallyunsaturated compounds such as allene, substituted ethenicallyunsaturated compounds such as 3-pentenenitrile, 4-pentenenitrile, methylpent-3-enoate, and combinations of two or more thereof; and ethenicallyunsaturated compounds having perfluoroalkyl substituents such as, forexample, C_(b)F_(2b+1), where b is an integer of up to 20. Preferredolefins are linear alkenes, linear alkenenitriles, linear alkenoates,perfluoroalkyl ethylenes, and combinations of two or more thereof. Mostpreferred olefins include 3- and 4-pentenenitrile, alkyl 3-, and4-pentenoates, and C_(b)F_(2b+1)CH═CH₂ (where b is 1 to 12), andcombinations of two or more thereof. 3-Pentenenitrile and4-pentenenitrile are the most preferred.

[0030] The preferred products are terminal alkane nitriles, lineardicyanoalkylenes, linear aliphatic cyanoesters,3-(perfluoroalkyl)propionitrile, and combinations of two or morethereof. Most preferred products are adiponitrile, alkyl5-cyanovalerate, C_(b)F_(2b+1)CH₂CH₂CN, where b is 1 to 12, andcombinations of two or more thereof.

[0031] The process of this invention can be carried out in the presenceof one or more Lewis acid promoters to affect both the activity and theselectivity of the catalyst system. The promoter may comprise aninorganic or organometallic compound in which the cation is selectedfrom the group consisting of scandium, titanium, vanadium, chromium,manganese, iron, cobalt, copper, zinc, boron, aluminum, yttrium,zirconium, niobium, molybdenum, cadmium, rhenium and tin. Examplesinclude, but are not limited to, ZnBr₂, ZnI₂, ZnCl₂, ZnSO₄, CuCl₂, CuCl,Cu(O₃SCF₃)₂, CoCl₂, CoI₂, FeI₂, FeCl₃, FeCl₂, FeCl₂(THF)₂, TiCl₂, TiCl₄(THF)₂, MnCl₂, ScCl₃, AlCl₃, (C₈H₁₇)AlCl₂, (C₈H₁₇)₂AlCl,(iso-C₄H₉)₂AlCl, Ph₂AlCl, PhAlCl₂, ReCl₅, ZrCl₄, NbCl₅, VCl₃, CrCl₂,MoCl₅, YCl₃, CdCl₂, LaCl₃, Er(O₃SCF₃)₃, Yb(O₂CCF₃)₃, SmCl₃, B(C₆H₅)₃,TaCl₅. Suitable promoters known in the art. These include metal salts,such as ZnCl₂, CoI₂, and SnCl₂, and organometallic compounds (such asR₈AlCl₂, R₈SnO₃SCF₃, and R₈B, where R₈ is an alkyl or aryl group). U.S.Pat. No. 4,874,884 (incorporated herein by reference) describes howsynergistic combinations of promoters can be chosen to increase thecatalytic activity of the catalyst system. Preferred promoters includeCdCl₂, FeCl₂, ZnCl₂, B(C₆H₅)₃, and (C₆H₅)₃Sn(CF₃SO₃), CH₃C₆H₅SO₃, or(C₆H₅)₃BCN. The mole ratio of promoter to Group VIII metal present inthe reaction can be within the range of about 1:16 to about 50:1.

[0032] Hydrocyanation can also be carried out with a conjugatedethylenically unsaturated olefin having from 4-15 carbon atoms,preferably 4 to 10 carbon atoms. With conjugated olefins, a Lewis Acidpromoter is optional. Examples of conjugated olefins containing fromabout 4 to about 15 carbon atoms are 1,3-butadiene, cis andtrans-2,4-hexadienes, cis and trans-1,3-pentadienes, and combinations oftwo or more thereof. Butadiene is especially preferred.

[0033] The following Formulae VI and VII illustrate some suitablestarting conjugated olefins. The products of the hydrocyanation process,as described herein, of 1,3-butadiene are represented in Formulas VIII,IX, and X:

CH₂═CH—CH═CH₂  VI

R₉CH═CH—CH═CHR₁₀  VII

[0034] (1,3-butadiene)

[0035] wherein each one of R₉ and R₁₀, independently, is H or a C₁ to C₃alkyl;

[0036] in which 3PN denotes 3-pentenenitrile, 4PN is 4-pentenenitrile,and 2M3BN is 2-methyl-3-butenenitrile.

[0037] The reaction of a conjugated olefin and a HCN-containing fluidcan be carried out in the same manner as that described above inrelation to monoethenically unsaturated compounds.

[0038] The catalyst compositions of the present invention may also beused in the isomerization of allylic nitrites. The catalyst compositionis combined with the allylic nitrile in a vessel and the isomerizationprocess is carried at from 0 degrees C. to 150 degrees C., andpreferably from 80 degrees C. to 120 degrees C. A solvent may be used.Examples of a suitable solvent include but are not limited to,hydrocarbons such as benzene, xylene, or combinations thereof; etherssuch as tetrahydrofuran (THF); nitrites such as acetonitrile,benzonitrile, adiponitrile, or combinations of two or more thereof.

EXAMPLES

[0039] The following non-limiting, representative examples illustratethe process and catalyst compositions of this invention. All parts,proportions, and percentages are by weight, unless otherwise indicated.In each example, the following procedure was used unless otherwisenoted.

Examples 1-27

[0040] Catalyst solutions were prepared by mixing one of the bidentateligands of the invention and Ni(COD)₂ in a molar ratio of 1.1:1 anddissolving this in toluene. To the catalyst solution was added asolution of the promoter in the trans-3PN. The promoter: nickel molarratio is 1.1:1. The molar ratio of trans-3PN to Ni was 200 equivalents.The reaction vessel was heated to the temperature as described in thefollowing Tables and hydrogen cyanide was delivered by slow evaporationof the hydrogen cyanide from a reservoir connected to the reactionvessel by a feed tube in an otherwise closed reaction system. Thereaction was analyzed after 15 hours. The reaction mixture was analyzedusing standard Gas Chromatograph methodology. Tables I-through III listthe conversion of pentenenitriles to dinitriles and the selectivity toadiponitrile, defined as the ratio of adiponitrile over all dinitriles,in this hydrocyanation reaction. TABLE I Promoter: ZnCl₂ Conversion toSelectivity to ligand Dinitrile ADN 50° C. Example 1

73.8 91.0 Example 2

2.2 81.8 Example 3

57.4 90.6 Example 4

32.7 87.6 Example 5

87.5 88.7 Example 6

28.2 85.1 80° C. Example 7

13.5 82.9 Example 8

58.8 73.0 Example 9

66.0 77.2 Example 10

83.2 73.7

[0041] TABLE II Promoter: ZnCl₂ Conversion to Selectivity for 50° C.Ligand Dinitrile ADN Example 11

40.5 90.0 Example 12

83.0 77.2 Example 13

74.4 86.2

[0042] TABLE III Conversion to Selectivity for 80° C. Ligand PromoterDinitrile [%] ADN [%] Example 14 Example 15 Example 16 Example 17

ZnCl₂AlCl₃Sesqui-AlCl CoCl₂  9.0 21.9 23.5 11.7 73.8 79.6 80.7 67.4Example 18 Example 19 Example 20 Example 21

ZnCl₂AlCl₃Sesqui-AlCl CoCl₂  9.8 24.2 34.7 12.7 80.8 81.7 86.0 75.9

Examples 22-25 Butadiene Hydrocyanation

[0043] 1,3-Butadiene Solution (BD): 1.56 g of BD were dissolved in 2 gof toluene. The resulting solution was stored in a sealed vessel at −35°C. until used.

[0044] HCN Solution: 0.93 g of liquid HCN was weighed into 1.9 g oftoluene. The resulting solution was stored in a sealed vessel at −35° C.until used.

[0045] Catalyst Solution: For a typical multidentate phosphonite ligand13 mmol of the bidentate ligand and 10 mmol of Ni(COD)₂ were combined intoluene to generate 3 g of catalyst solution.

[0046] In the examples as shown in Table IV, the butadienehydrocyanation processes were carried out as described below.

[0047] To a reaction vessel were added 0.1 ml of the catalyst solution.To this was added 0.18 g of the butadiene solution followed by 0.14 g ofthe HCN solution. The vessel was sealed and placed in a reactor set at100° C. Samples were removed after three hours.

[0048] Table IV lists the productive conversion of butadiene to 2M3BN,c,t-3PN, 4PN (total PN) and the ratio of 3PN/2M3BN, which was analyzedby GC method. TABLE IV % Total PN 3PN/2M3 Example 22

79.4 0.38 Example 23

83.7 0.73 Example 24

82.0 0.76 Example 25

31.2 0.42

Examples 26-27 Isomerization of 2-methyl-3-butenenitrile to3-pentenenitrile

[0049] For a typical multidentate phosphonite ligand of the invention0.008 g of Ni(COD)₂ was mixed with 0.032 mmol of the ligand anddissolved in 0.8 g of toluene. To this was added 0.56 g of 2M3BN. Thereactor was closed and heated to 100° C. The reactions were analyzedafter 4 hours and 8 hours reaction time. The reaction mixture wasanalyzed using standard GC methods. The ratio of 2M3BN to 3PN is listedin Table V. TABLE V Ratio of 3PN/2M3BN Entry Ligand 4 hrs 8 hrs 1

24.2 25.6 2

20.1 24.6 3

1.4 5.2

What is claimed is:
 1. A hydrocyanation process, said processcomprising: contacting an ethylenically unsaturated olefin compound withHCN in the presence of a catalyst composition, wherein said catalystcomposition comprises a Group VIII metal and a phosphonite ligandwherein the ligand having a structure selected from the group consistingof:

wherein the X groups are either the same or different unbridged organicaromatic groups as described in Formula I, wherein Q is a substituted orunsubstituted divalent aromatic or non aromatic hydrocarbon radical. Thesubstituent on the Q groups is independently selected from the groupconsisting of C1 to C12 alkyl, cycloalkyl, alkoxy, alkylaryl, aryl,hetero aryl, cyano
 2. A hydrocyanation process according to claim 1wherein X is selected from the group consisting of substituted orunsubstituted phenyl, substituted or unsubstituted naphthyl, andcombinations thereof.
 3. A hydrocyanation process according to claim 1wherein the X is selected from the group consisting of:


4. A hydrocyanation process according to claim 1 wherein saidethylenically unsaturated compound is a conjugated C₄ to C₂₀ diene. 5.The process of claim 1 wherein the ethylenically unsaturated compound isbutadiene.
 6. The process of claim 1 wherein reactants are in the liquidphase.
 7. The process of claim 1 wherein the Group VIII metal isselected from the group consisting of nickel, cobalt, and palladium. 8.The process of claim 1 wherein said Group VIII metal is a zero-valentnickel.
 9. The process of claim 1 wherein the unsaturated compound is an-pentenenitrile.
 10. The use of a catalyst based on a ligand ofstructure II for the hydrocyanation and/or the positional isomerizationor double bond isomerization of olefins.